Compressional wave translating device



Jan. 20, 1948. w. D. momma, R, :r AL 2,434 48 mBEssIoNAL WAVE TRANSLATING DEVICE Fi led June 2. 1943 nvvmroes ATTORNEY Patented Jan. 20,1948

.UNITED STATES. PATENT OFFICE.

, COMPRESSIONAL WAVE TRANSLATING DEVICE Walter B. conclusion, t OrangeiN phone Laboratories} N. Y., acorporation of Convent, and Thomas J. J., asalgnors to Bell Tele- Incorporated,

York

New York,

Appllcationlune 2, ms, Serial No. ream 11 Claims. (01.177-388) This invention relates to compressional wave translating devices and more particularly to sultigrsonic projectors for submarine signaling sys- The present inventionis an improvement upon that disclosed in the copending application Serial No 470,808, filed December 3 1, 1942, of Arthur C. Keller.

One object of this invention is to obtain a substantially circular directional propagating pat-' tern for a supersonic projector, whereby the pro- Jector will propagate signals with substantially features thereof will be understood more'clearly and fully from the following detailed-description with reference to the accompanying drawing, in which: 7

Fig. 1 is a perspective view of a submarine signaling device illustrative of one embodiment of a the invention, portions of the housing and supuniform intensity in all directions about an axis thereof and will propagate relatively little along this axis. x

Another object of this invention is to increase the power capacity of supersonic submarine signalin devices of the piezoelectric type.

A further object of this invention'is to simplify and facilitate the'construction of high power submarine signaling devices.

In one illustrative embodiment ofthis'invene,

a supersonic submarine signaling device comprises a housing transparent toqcompres-J and filled with an air-free fluid having substantially the same transmission characteristics for supersonic compressionaltwave energ as sea water-and a piezoelectric trans- 5 the housing and immersed.- in

tion,

sional wave energy latlng unit within the fluid filling therein.

In accordance with one feature of this inYention, the translating unit comprises an array of an elongated, cylindrical cup-shaped housing ll fsealed in water-tight relation to the casing ill and of a material transparent to supersonicvcompresher in which the elements of as acompressionalwave submarine projector at supersonic; frequencies, for example frequencies of the" order 01125 lrilocycles per second. It comprises a, water-tight casing III in which a transformer or other apparatus may be mounted and sional wave'energy and having substantially the substantially identical piezoelectric elements of square cross-section mounted in superposed and, adjacent elements having axes at rightangles to onean-' i other 'so that-adiacent'units vibrate at: right r aligned relation their mechanical angles to one another in r'esponseto electrical sl'g- I nals impressed thereon.

In accordance with another name of this icanized to the casing l0.

invention, the several elements of the array are associated electrically in two groups, the ele'- ments of the twogroups being in alternate relation, and the two groups are energized 90 degrees out of phase with one another whereby a substantially circular propagation pattern about .the longitudinal axis of the array is obtained.

In accordance with a further feature of this invention. the several elements constituting the array are mounted single support by common fastening elements, adjacent elements being spaced slightly by thin interposed sheets or layers of a material having small mechanical impedance. 7

The invention and the above-noted and other in pile-up fashion upon a -F'lgi'2, comprises a plurality,

same density and wave transmission velocity characteristic as sea water. In one form; the housing ll may be of rubber having the characteristics noted and having Supported upon a plate I! joined to. the casing 1 illiat one end thereof is an array Of piezoelectric Jcry'stal elements I 3, the element I3 nearest the r plate l2 belngseated upon and spaced from the "plate l1 by a block H seated on the plate, Each 40 shown clearly in for example four, of similar rectangular piezoelectric slabs or blocks l5 secured together in face-to-face relation. The slabs or blocks ii are of such dimensions that each element I3 is of square cross-section and the array provides, therefore, four equalarea propagating surfaces in quadrature. Opposite faces 01', the slabs are provided with electrodes l6, such as electrically conductive coatings suitably applied of the crystal elements II, as

- to these faces, to which leading-in conductors i1.

such as foil strips, are secured. The several slabs or blocks i 5 constituting each element i3 have their mechanical axes parallel and have their electrical axes oriented so that the slabs or blocks vibrate in the same direction in response to signal its open end vulright angles. All the elements i3, together with the block I, are secured in common between the plate i2 and a clamping plate 19 by posts or bolts 20 connecting the plates l2 and I9 and disposed opposite the corners of the crystal array.

As illustrated in Fig. 2, advantageously the several elements I3 are associated electrically in two groups by conductors 2i and 22, which are connected to a suitable signal supply source 40 in such manner that the two groups of elements are energized 90 degrees out of phase and with the same amplitude.

The housing I l is filled with afiuid, not shown,

' such for example as castor oil. having substantially the same transmission characteristics for supersonic compressional wave energy as sea water.

When the elements l3 are energized, as noted above, each of the elements vibrates in the direction normal to the major faces of the blocks or slabs thereof, the direction of vibration of the two groups of elements being -at right angles. Hence, the array as a whole propagates compressional waves of substantially uniform intensity in all directions normal to the longitudinal axis of the array, that is, the directional pattern of the array is circular about the longitudinal axis of the array. 'I'heintenslty of propagation along the axis is small so that the array is essentially non-directional parallel to this axis. Because of the sheets or layers It, each element I3 vibrates substantially independently of the adjacent elements, as noted heretofore, so that interference between adjacent elements and, hence, distortion are eliminated. The block l4 spaces the element 13 seated thereon from the plate l2 and thus prevents interference by the plate with the waves propagated by this element.

In.the construction illustrated in Figs. 3 and 4, the electrically conductive coatings upon each face of the crystal slabs or blocks l5 are divided to provide two electrodes Mia and Iiib on each face, and diagonally opposite electrodes on the two faces of each slab or block are connected to one another as by conductive coating strips 23, one of which is shown in Fig, 3.

The elements l3 including blocks or slabs of the construction shown in Fig. 3 may be square or may be rectangular as illustrated in Fig. 4. The phase pattern resulting when the two groups of elements are energized 90 degrees out of phase with one another is indicated in the latter figure and constitutes in effect a continuous phase rotation resulting in non-directivity about the axis of the crystal array.

In a modification of the construction illustrated in Fig. 3, each crystal block or slab may be composed of two separate parts, the mechanical division corresponding to the electrical division of the conductive coatings into two parts.

It will be appreciated that the crystal array provides an efficient device of high power capacity and. low impedance which is of relatively simple proximately 15 watts in a medium of castor construction and may be constructed with facility. In a typical device, the array may be of the order of 4 inches long and each element l3 may be of the order of inch on a side. Whn the slabs or blocks I5 are of Rochelle salt, the power capacity of a device of these dimensions is apoil.

It will be understood, of course, that arrays of different dimensions and composed of a greater or lesser number of elements l8 may be employed. It will be understood further that the particular device shown and described is but 11- lustrative and that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended'claims.

What is claimed is:

1. A compressional wave translating device comprising an elongated electromechanical translating unit of substantially square cross-section, said unit including a plurality of similar piezoelectric crystals in superposed relation and oriented so that the axes of expansion and contraction of adjacent crystals are in parallel planes and at right angles to one another and flexible means interposed between and spacing adjacent crystals.

2. A compressional wave translating device comprising a plurality of similar piezoelectric crystals in superposed aligned relation and defining an elongated electromechanical translating unit of substantially square cross-section, said crystals being vibratile normal to the axis of alignment thereof and adjacent crystals having their axes of vibration at right angles to one another, and spacer means having low mechanical impedance interposed between adjacent crystals.

3. A supersonic compressional wave projector comprising a linear array of similar piezoelectric elements of substantially square cross-section and having their .corresponding faces coplanar, said elements being mounted in superposed rela tion with the axes of expansion and contraction of adjacent elements at right angles to one another, thin flexible sheet means interposed between and spacing adjacent elements, and means for electrically driving all of said elements to cause vibration thereof normal to the longitudinal axis of said array.

4. A supersonic compressional wave projector comprising an elongated electromechanical translating element including a plurality of similar rectangular piezoelectric crystals mounted for vibration in the longitudinal mode and in superposed relation and oriented so that the axes of expansion and contraction of adjacent crystals are at right angles to one another, means for electrically energizing one group of alternate crystals, and means for energizing the remainder of said crystals electrically at the same amplitude as and substantially degrees out of phase with said group of alternate crystals.

5. A supersonic compressional Wave projector comprising two groups/of piezoelectric crystals mounted in superposed aligned relation with the groups of crystals at the same amplitude and substantially 90 degrees out of phase.

6. A-supersonic compressional wave projector comprising two groups of substantially square piezoelectric crystals mounted in aligned superposed relation with the crystals of one group in alternate relation with and having their mechanical axes parallel and at right .angles to the crystals or the other group, means of low mechanical impedance interposed between and spacing adjacent crystals, each of said crystals including a plurality of crystal slabs mechanically and electrically oriented to vibrate in phase, and means for energizing said groups of crystals at the same amplitude and substantially 90 degrees out of phase.

7. A compressional wave translating device comprising an array of similar, substantially square piezoelectric crystals mounted in aligned superposed relation with the axes of expansion and contraction of adjacent crystals at right angles to one another, flexible means interposed between and spaced adjacent crystals, 5. support adjacent one end of said array of crystals, and means clamping said crystals to one another and to said support.

8. A supersonic compressional wave projector comprising two groups of similar, substantially square piezoelectric elements in aligned superposed relation with the elements of the two groups in alternate relation, each of said elements including a plurality of slabs mechanically and electrically oriented to vibrate in phase, the axes of vibration of said groups being at right angles to one another, flexible means interposed between and spacing adjacent elements, a support, means securing said elements in alignment and to said support, and means for driving said groups 01' elements at the same amplitude. and substantially 90 degrees out of phase.

9. A compressional wave signal translating device comprising two groups of piezoelectric elements mounted in superposed relation with the elements oi. one group in alternate relation with and having their axes of expansion and contraction at right angles to those 01' the elements of the other group, each or said elements including piezoelectric crystal slabs in i'ace-to-face relation, twoelectrodes upon each face 01' each slab and extending i'rom adjacent opposite means connecting diagonally opposite electrodes on the opposite races of each slab, and means connected to said electrodes for energizing said ends thereof,

groups at substantially the same amplitude and so substantially degrees out of phase.

agonaily opposite electrodes 10. A compressional wave signal translating device comprising two groups of electromechanical translating elements mounted in superposed relation with the elements of the two groups in alternate relation, each of said elements comprising a plurality of rectangular piezoelectric crystal slabs in race-to-face relation and the slabs oi the two groups of elements being oriented so that the rectangular piezoelectric crystals, the crystals of the two groups being in alternate relation and having their axes of expansion and contraction at right angles, each crystal comprising a plurality of slabs mounted in face-to-face relation and oriented to vibrate in unison, two electrodes on each face of each slab and on opposite sides-oi. the median line of the face, means connecting dion opposite faces of each slab, whereby each slab includes two sections electrically associated to vibrate substantially degrees out of phase, the slabs of each crystal being oriented so that corresponding sections vibrate in phase, and means connected to said electrodes tor energizing the two groups of crystals at substantially the same amplitude and 90 degrees out of phase.

WALTER D. GOODALE, JR. THOMAS J. POPE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Brltain------- Feb. 21, 1930 

